Fix the Bind to port 22 on 0.0.0.0 failed - Address already in use error

The error when starting and restarting sshd : Mar 30 23:35:11 x sshd[9151]: Server listening on :: port 22. Mar 30 23:35:11 x sshd[9151]: error: Bind to port 22 on 0.0.0.0 failed: Address already in use. Mar 30 23:38:07 x sshd[9151]: Received signal 15; terminating. Mar 30 23:38:07 x sshd[1977]: Server listening on :: port 22. Mar 30 23:38:07 x sshd[1977]: error: Bind to port 22 on 0.0.0.0 failed: Address already in use.

A successful connection made to the server despite the issue : Mar 30 23:40:46 x sshd[2421]: Accepted publickey for root from ::ffff:xxx.xxx.xxx.xxx port 13586 ssh2

**The fix : disable IPv6 : ** echo "alias net-pf-10 off" >> /etc/modprobe.conf restart the machine

Restarting the machine with IPv6 disabled : Mar 30 23:47:57 x sshd[1957]: Server listening on 0.0.0.0 port 22. Mar 30 23:48:46 x sshd[2470]: Accepted publickey for root from xxx.xxx.xxx.xxx port 13600 ssh2